A 3D printer or a machine tool according to the related art is required to exchange a tool of an end effector or attach a touch sensor including a device such as a servo motor, an actuator, a servo arm, a touch switch, a proximity sensor, and the like thereto to detect a horizontality or position of an object (or bed: hereinafter, referred to as an object).
FIG. 14 is a view showing a touch sensor for detecting a position or horizontality of an object of a 3D printer according to the related art, where the touch sensor includes a servo motor 55, a servo arm 56 and a touch switch 57 which are provided to a side surface of an end effector 50 of the 3D printer. To detect a position or a degree of horizontality of a detection object 90, the 3D printer operates the servo motor 55 of the touch sensor to allow the touch switch 57 formed on one end of the servo arm to face the detection object 90 positioned below the 3D printer. Then, the 3D printer moves the touch switch 57 or the detection object 90 in the direction that allows the gap between the touch switch 57 and the detection object 90 to be narrowed until a detection signal generated from the touch switch 57 is input thereto. When the detection signal is input, the 3D printer calculates the position of the sensing object 90. When the detection is terminated or an emergency occurs, the 3D printer operates the servo motor 55 to move upward the touch switch 57 formed on one end of the servo arm 56, thereby preventing the touch switch 57 from interfering with a next operation.
Meanwhile, the touch switch 57 generates the detection signal when the detection object 90 approaches the touch switch 57 while the detection object 90 makes contact with the touch switch 57 to be pressed so that the interval is less than a predetermined interval.
The above-described sequence of process is a function basically provided from a 3D printer or machine tool of the related art, where the degree of horizontality (slope) of the detection object is generally calculated as a measurement value of three points or more.
Thus, to employ an expensive automatic tool changer or an automatic detection device having a complex structure, the entire volume of the end effector 50 is increased so that the size of a possible output is relatively reduced, thereby causing spatial restriction, inefficiency and heat in the end effector and the bed (working table).
Specifically, some non-contact sensors used for solving the above-described problems require that the detection object is formed of only a specific material such as metal, and cause a serious error even in the case of a detection object made of a material such as metal or glass.
In recent years, although there has been grown a demand for an automatic detection function in order to speed up work, improve efficiency, and reduce labor force, there have been many difficulties in automation due to the above-described problems.
Meanwhile, a touch sensor or an end effector has been developed in various forms for the purpose of detecting the horizontality or position of an object in a 3D printer. A nozzle unit including an automatic leveler and a material cooling part has been disclosed in Korean Unexamined Patent Publication No. 10-2015-0098340. A 3D printer including a horizontal measurement sensor unit has been disclosed in Korean Unexamined Patent Publication No. 10-2016-0027666.